An elderly, wealthy West Australian businessman has been found guilty of attempting to hire a hitman to murder his son's ex-wife.

Brian Vincent Attwell, 73, has been on trial in the Albany Courthouse on the state's southern coast for the past five days, charged with the rare offence of attempting to procure the commission of a crime.

The court heard the accused asked a truck diver, who approached him desperate for work with his civil contracting company AD Contractors, to kill 50-year-old Michelle Patreena Attwell after becoming frustrated with a protracted, bitter legal dispute between her and his son following the breakdown of their marriage.

The driver informed police, who instructed him to set up a meeting between Attwell and an undercover policeman.

Attwell met the policeman twice at a beach near the woman's home, and paid A$10,000 in two instalments as a down payment on a A$30,000 job.

The court heard Attwell refer to her as a "maggot", a "pain in the arse" and a "nuisance to society" who should be "put to sleep".

He told the officer to bind Attwell in duct tape, strangle her and bury her in a 30-foot hole dug by an excavator.

Defence lawyer Tom Percy argued his client was just expressing his frustration with the ongoing legal dispute, a central point of contention being his son's stake in AD Contractors, a multi-million dollar business.

Attwell repeatedly said during his testimony that his hateful comments were "huff and puff", and that he only wanted his estranged daughter-in-law frightened.

But state prosecutor James MacTaggart said evidence showed Attwell was committed to having her murdered.

Percy argued the undercover policeman had not been given enough information about Attwell - including a photograph - for her to have been in real danger.

MacTaggart, however, said Attwell had provided an address and general description, and that was sufficient for the woman to be at serious risk.

On Friday, a jury convicted Attwell, who spent six months in custody after he was charged.

They deliberated for more than three hours over two days.

MacTaggart noted Attwell was ill and barely mobile, but said he deserved a substantial term of imprisonment as he had engaged a contract killer to a party in a legal dispute.